Within the scope of a previously completed NIH developmental grant (R33CA99059), we successfully demonstrated a real-time synthetic aperture volumetric ultrasound imaging system for use in an endoscope channel. This system was based on a 16x16-element two-dimensional capacitive micromachined ultrasonic transducer (CMUT) array integrated with front-end transmit-receive integrated circuits. The backend of the system consisted of a 16-channel analog-to-digital converter and a field programmable gate array used for data acquisition and image reconstruction. In a 4-year program, we aim to expand the current system for larger arrays with a larger number of active electronic channels implementing scalable phased array beamforming schemes to improve the image quality. We plan to increase the array size to 32x32 and eventually to 64x64 in this project. The described system will be available for intracavital ultrasound imaging to improve the diagnosis, staging and therapy of various cancers. The clinical validation will be the subject of a follow-up grant. The specific aims of the proposed work are as follows: 1. Design and construct 32x32 and 64x64-element 2-D CMUT arrays 2. Design front-end integrated circuits for real-time 3-D ultrasound imaging 3. Improve the backend data acquisition system to process more channels in parallel 4. Integrate system components The research team put together for the proposed work combines expertise in the fields of acoustics, system design, signal processing and clinical applications. PUBLIC HEALTH RELEVANCE: The successful development of a real-time, 3-D miniature ultrasound imaging system will significantly improve the accuracy in the diagnosis and therapy of various diseases. We propose to develop an integrated intracavital transducer probe and the supporting imaging system that can be used for numerous applications, in which an image is required to be obtained from within a natural body cavity or an artificial channel such as a laparoscope. Some of the potential applications of this novel probe include preoperative staging of colorectal cancer, real-time interactive transrectal ultrasound guided prostate brachytherapy, and image-guided minimally-invasive transgastric procedures.